Flock Level Research Articles

Seroprevalence of Q fever among ewes and associated risk factors in Ain Defla region, North-central Algeria

Q fever is a zoonotic disease caused by Coxiella burnetii, which causes abortions in domestic ruminants. This study aims to assess the seroprevalence of Q fever among ewes and investigate the associated risk factors in the Ain Defla region (north-central Algeria). Blood samples from 184 ewes were randomly collected from 45 sheep flocks. Sera were tested for the presence of antibodies against C. burnetii using an ELISA test. Seroprevalence was 24.9% and 66.7% at the animal and flock levels respectively. Univariate analysis at the animal level indicated three factors significantly associated with C. burnetii seropositivity: presence of pigeons in farms (χ2 = 9.689; p = 0.008), abortion in ewes (χ2 = 11.209; p = 0.001), and abortion history in the flock (χ2 = 7.744; p = 0.005). Therefore, C. burnetii infection plays a major role in abortions in the sheep populations under study, and the presence of pigeons in farms plays a role in disease transmission.

Prevalence and antimicrobial resistance of Salmonella enterica subsp. diarizonae serovar 61:k:1,5,(7) in Swiss sheep flocks

Salmonella (S.) enterica subspecies diarizonae (IIIb) serovar 61:k:1,5,(7) (S. IIIb 61:k:1,5,(7)) is considered to be sheep-associated, as it can be found in the intestine, tonsils and nose of clinically healthy sheep, but it has also been described in separate clinical disorders in sheep. In particular, S. IIIb 61:k:1,5,(7) is described as the causative agent of chronic proliferative rhinitis (CPR) in sheep. In Switzerland, CPR in sheep due to S. IIIb 61:k:1,5,(7) was first described in 2017 in a flock of Texel sheep. Therefore, we assessed the prevalence of S. IIIb 61:k:1,5,(7) within the Swiss sheep population using a representative sampling strategy. From May 2017 to June 2018 a total of 681 nasal swabs from individual clinically healthy sheep of 141 different flocks throughout Switzerland were taken. Swabs were analysed by selective enrichment for the presence of S. IIIb 61:k:1,5,(7). Additionally, antimicrobial resistance of the isolates was determined by broth microdilution. A total of 146 out of 681 nasal swabs tested positive for S. IIIb 61:k:1,5,(7), which corresponds to a prevalence on animal level of 21% (95%CI 18%−25%). In 73 out of 141 flocks tested, at least one sheep tested positive for S. IIIb 61:k:1.5,(7), resulting in a minimal prevalence on flock level of 52% (95%CI 43%−60%). Positive flocks were found in all cantons except the canton of Jura. Adults were significantly more affected than sheep under one year/lambs and positive sheep were found in several breeds. No microbiologically resistant isolates were detected, except for one isolate showing resistance against ampicillin. Because of its widespread occurrence in the Swiss sheep population, further research should focus on the pathogenic impact of S. IIIb 61:k:1,5,(7) on the health status of sheep.

Transmission dynamics and economic impacts of sheeppox and goatpox disease outbreak in Chifra district of Afar Region Ethiopia

Sheep and goatpox are caused by pox virus and economically very important. The study was conducted to estimate the economic losses due to sheep and goatpox, to estimate the morbidity and mortality as well as the transmission parameters. A cross sectional study was conducted in Chifra districts of Afar region from July 2020 to December 2020 using questioner survey. For the estimation of the economic impacts and the transmission parameters of the outbreak, a data was collected at the end of the outbreak through a direct face to face interview. Transmission parameters were estimated based on a final size approach. Whereas, economic impacts were estimated descriptively using different formulas based on the type of losses. The overall morbidity, mortality and case fatality of sheep and goatpox were 51.6%, 2.0%, and 3.9%, respectively. The average flock level losses due to treatment cost, mortality and abortion were 320.3, 1250 and 1195.6 Ethiopian birr (ETB), respectively. The outbreak caused a total of 63617 ETB losses in the district. The highest loss was due to mortality (28750ETB), whereas the least loss was due to treatment cost (7367ETB). The outbreak had 0.14 and 1.41 transmission rate parameters per day and basic reproduction ratio, respectively. There was a significant difference in the transmission of the infection between individual animals (p < 0.001). To limit the economic losses due to this disease, the farmers should give more attention towards this disease and a systematic control program comprising vaccination and limitation of movement of sheep and goat should be implemented to alleviate the losses due to sheep and goatpox.

Sheep scab in Northern Ireland: Its distribution, costs and farmer knowledge about prevention and control

Sheep scab (psoroptic mange), which is endemic in the United Kingdom (UK) flock, has a significant, negative impact on sheep welfare. Nothing has previously been published about the distribution of sheep scab in Northern Ireland (NI), nor about Northern Irish farmers’ knowledge and behaviours relating to the disease, its treatment, prevention and control. Between March and June 2021 an online questionnaire on the disease was completed by sheep farmers in NI. Forty-four respondents out of a total of 122 valid returns (36%) indicated that they had at least one outbreak of sheep scab in their flock within the previous five years. These flocks were spread throughout NI and included flocks grazing on common land. Farmers reporting sheep scab in their flock considered movements of sheep between flocks to be the main cause of flock infestation. Respondents demonstrated knowledge gaps in relation to the parasite biology, disease transmission, prevention and treatment options, as well as a lack of awareness of some of the relevant industry guidelines. We highlight that some farmers rely on clinical signs alone to rule out the possibility that newly purchased sheep are infested with sheep scab before mixing them with their flock. This activity poses a high risk for the introduction of sheep scab into previously uninfested flocks. The inadequacy of some farmers’ quarantine rules, or their inability to follow them, was also reported by farmers as being the cause of their flock infestation. Sheep scab outbreaks were shown to result in significant financial cost, with some farmers reporting their most recent outbreak had cost over £2500 ($3329). The paper also highlights that in addition to the animal health and welfare impact and financial cost, sheep scab was reported to have a social cost: 94 respondents (79%) agreed that a sheep scab outbreak caused emotional stress to affected farmers. These findings have provided evidence of the widespread nature of sheep scab in the NI flock, and of the knowledge gaps and behaviours which need to be addressed to improve sheep scab control. This will require a combination of focused research, knowledge exchange between farmers, advisors, policy makers and regulators, and co-developed disease control plans at a flock and national level.

Economic impact of a peste des petits ruminants outbreak and vaccination cost in northwest Ethiopia.

Peste des petits ruminants (PPR) is an important endemic disease of small ruminants in Ethiopia. While vaccination is widely used in the country to control the disease, quantitative estimates of the actual economic losses due to outbreaks and costs of vaccination are scarce. This study assessed the economic impact and costs of PPR vaccination in Metema district, northwest Ethiopia. The economic impact of the disease was estimated from an outbreak investigation including interviews with 233 smallholder farmers in PPR-affected kebeles (subdistricts). The cost of PPR vaccination was obtained from vaccination programs in six kebeles of the district and from secondary data in the district veterinary office. In the investigated PPR outbreak, animal-level PPR morbidity and mortality rates were 51% and 22%, respectively, in sheep and 51% and 25%, respectively, in goats. The flock level morbidity rate was 83% for sheep flocks and 87% for goat flocks. The mean flock level loss was Ethiopian Birr (ETB) 7835 (USD 329 in 2018 average exchange rate) (95% CI: 5954-9718) for affected sheep flocks and ETB 7136 (USD 300) (95% CI: 5869-8404) for affected goat flocks. The losses in all study flocks during the outbreak were ETB 319 (USD 13.4) per sheep and ETB 306 (USD 12.9) per goat. Mortality accounted for more than 70% of the total losses in both sheep and goat flocks. Vaccination costs for PPR were estimated at ETB 3 per correctly vaccinated animal. Based on the estimated animal-level direct economic losses and vaccination cost, it can be conjectured that vaccination will pay if a district PPR outbreak occurs more than once every 13 years. This does not account for additional benefits from vaccine-derived herd immunity reducing disease burden in the wider population. In conclusion, PPR caused high morbidity and mortality in the affected flocks and resulted in high economic losses, equivalent to 14% of annual household income, dramatically affecting the livelihoods of affected flock owners. The vaccination practised in the district is likely to have a positive economic return, with strengthened vaccination programmes bringing reduced economic impact and improved livelihoods.

Serological Diversity of Dichelobacter nodosus in German Sheep Flocks.

Simple SummaryFootrot is an infectious hoof disease in sheep, caused by the bacterium Dichelobacter nodosus. The antigentic variation of the fimbrial proteins resulted in the description of up to ten serogroups (A–I and M). Vaccines against footrot target these fimbrial variants. Commercial vaccines are covering nine serogroups but have low efficacy compared to vaccines based on two serogroups. Therefore, our study investigated the prevalence and distribution of the nine serogroups A–I in German sheep flocks with the aim to detect the predominant serogroups guiding optimized vaccines based on two serogroups. Serogroup A was most common in our study, followed by serogroups B, H and C. More than one-third of the animals showed more than one serogroup. In flocks, we found, on average, 3.10 serogroups in a range of one to six. The nine serogroups were widely distributed across the flocks, with 50 different combinations across the 83 flocks investigated. The lack of two predominant serogroups in Germany impairs the nationwide protection against footrot by the usage of more efficient vaccines based on two serogroups and requires tailor-made flock-specific vaccines.Footrot is one of the major causes of lameness in sheep and leads to decreased animal welfare and high economic losses. The causative agent is the Gram-negative anaerobic bacterium Dichelobacter nodosus. The prevalence of D. nodosus in 207 sheep flocks across Germany was 42.9%. Based on the sequence variation in the type IV fimbrial gene fimA, D. nodosus can be subdivided into ten serogroups (A–I and M). There are commercially available vaccines covering nine serogroups, but the efficacy is low compared to bivalent vaccines. The aim of this study was to investigate the diversity of serogroups in Germany at the flock and animal levels. In total, we detected at least one serogroup in 819 samples out of 969 D. nodosus-positive samples from 83 flocks using serogroup-specific singleplex PCR for the serogroups A–I. Serogroup A was most prevalent at the animal level, followed by serogroups B, H and C. At the flock level, serogroups A and B had the highest prevalence, each with 64%, but only 40% of flocks had both. The average number of serogroups per animal was 1.42 (range one to five) and, per flock, 3.10 (range one to six). The serogrouping showed within-flock specific clusters but were widely distributed, with 50 different combinations across the flocks. The factors associated with the number of serogroups per animal and single serogroups were the load of D. nodosus, footrot score, sheep breed and flock. Our results indicate that efficient vaccination programs would benefit from tailor-made flock-specific vaccines and regular monitoring of circulating serotypes in the flock to be able to adjust vaccine formulations for nationwide progressive control of footrot in Germany.

High sequence similarity between avian pathogenic E. coli isolates from individual birds and within broiler chicken flocks during colibacillosis outbreaks

Avian pathogenic E. coli (APEC) cause high first week mortality (FWM) in broiler chickens worldwide. In order to investigate the epidemiologic aspects of colibacillosis in broiler flocks it is important to develop reliable and cost-effective sampling guidelines. In this context, it is particularly important to define the minimum number of samples required to reliably identify the causative APEC clone during outbreaks of colibacillosis.This study describes the diversity of E. coli isolates between and within three flocks with high FWM due to colibacillosis. Each flock was represented by five animals, showing typical lesions of colibacillosis, and spleen, liver and one other organ from each animal was sampled for APEC. A total of 47 E. coli isolates, one per organ, and approximately 15 isolates per flock were whole genome sequenced and compared by multilocus sequence typing (MLST), serotyping and phylogenetic analysis to deduce their relationship. The results revealed that within individual birds there was little or no sequence type (ST) or serotype diversity between APEC isolates from different organs. Based on phylogenetic analysis, isolates belonging to the same ST and serotype showed a low number of single nucleotide polymorphisms (SNPs) across more than 95 % of the genome. Isolates from the liver always represented the major disease-causing APEC in individual birds, even when more than one ST was detected within an individual bird and flock. This study guides us towards an economically efficient way of sampling for future epidemiological studies on colibacillosis, by determining the causative APEC-clone at flock level.

Prevalence of Newcastle disease and associated risk factors in domestic chickens in the Indian state of Odisha.

Newcastle disease (ND), caused by Newcastle disease virus (NDV), is a contagious disease that affects a variety of domestic and wild avian species. Though ND is vaccine-preventable, it is a persistent threat to poultry industry across the globe. The disease represents a leading cause of morbidity and mortality in chickens. To better understand the epidemiology of NDV among commercial and backyard chickens of Odisha, where chicken farming is being prioritized to assist with poverty alleviation, a cross-sectional study was conducted in two distinct seasons during 2018. Choanal swabs (n = 1361) from live birds (commercial layers, broilers, and backyard chicken) and tracheal tissues from dead birds (n = 10) were collected and tested by real-time reverse transcription polymerase chain reaction (RT-PCR) for the presence of matrix (M) and fusion (F) genes of NDV. Risk factors at the flock and individual bird levels (health status, ND vaccination status, geographical zone, management system, and housing) were assessed using multivariable logistic regression analyses. Of the 1371 samples tested, 160 were positive for M gene amplification indicating an overall apparent prevalence of 11.7% (95% CI 10.1–13.5%). Circulation of virulent NDV strains was also evident with apparent prevalence of 8.1% (13/160; 95% CI: 4.8–13.4%). In addition, commercial birds had significantly higher odds (75%) of being infected with NDV as compared to backyard poultry (p = 0.01). This study helps fill a knowledge gap in the prevalence and distribution of NDV in apparently healthy birds in eastern India, and provides a framework for future longitudinal research of NDV risk and mitigation in targeted geographies—a step forward for effective control of ND in Odisha.

Seroprevalence and Associated Risk Factors of Ovine Brucellosis in South Omo Zone, Southern Ethiopia.

BackgroundBrucellosis is a zoonotic disease with economic and public health significance in developing countries that rely on livestock production including Ethiopia. This study intended to establish the seroprevalence and associated risk factors of ovine brucellosis.MethodsA cross-sectional study was carried out on seroepidemiology of ovine brucellosis from January 2017 to June 2020 G.C in five districts of South Omo zone, Southern Ethiopia. A total of 1536 sera samples were collected from sheep and serially tested using modified Rose Bengal plate test, competitive enzyme-linked immunosorbent assay, and complement fixation test to detect antibodies against natural infection by Brucella species. A structured questionnaire was used to collect data from individual animals, and flocks for the analysis of the association between expounding and outcome variables. Data were analyzed using STATA version 14.0 and potential risk factors for seropositivity of brucellosis were analyzed using logistic regression.ResultsThe study discovered an overall 5.40% (95% CI: 6.34, 14.25) and 39.74% (95% CI: 6.50, 6.97) seroprevalence of ovine brucellosis at individual and flock level, respectively, by a confirmatory test. Age groups, sex, flock size, district, history of abortion, and body condition were significantly associated risk factors with Brucella seropositivity (p < 0.05).ConclusionTo conclude, the prevalence of ovine brucellosis in the South Omo Zone was relatively high which needs integrated intervention approaches in place to curb the spread of the disease.

Ewe colostrum quality on commercial Welsh sheep farms

In advance of the 2020 lambing season, 147 Welsh farmers were engaged in active colostrum management through training and discussion groups. Sixty-four of these farmers returned data on 1295 ewes, including ewe age, breed, body condition score (BCS), number of live and dead lambs born, a description of udder condition, colour of colostrum and a Brix reading. Flock numbers were available from 43 farmers and information on late pregnancy ration from 30 farms. Results were analysed using a Brix reading cut-off of 26.5% and showed that 76% of samples exceeded this level and were considered of good quality. With an average of 20 ewe colostrum samples returned per flock, the greatest variation was found to be at the flock level with ewe nutrition considered to be the greatest driver. Concentrate feed space, silage crude protein and the supplementation of concentrates to twin and triplet-bearing ewes were all factors that indicated a potential flock level role in determining the colostrum quality. Individual level ewe factors appeared to have a much smaller role in determining the quality of the colostrum, with the ease of stripping being the main significant factors. Colostrum quality was more likely to be inadequate if the ewe was reported to be hard to strip (OR 0.56). While not significant in the final regression model, other ewe factors appeared to have an impact on the colostrum quality, such as the BCS and number of lambs born; however, lack of significance in the model may mean they are not significant or that they reflect differences in management between different flocks. As UK sheep farmers prepare for lambing 2022, and continue to optimise colostrum management and reduce levels of antibiotic given to neonatal lambs, this practical study has demonstrated how sheep farmers can be actively motivated to measure colostrum quality to determine how to optimally manage colostral antibody delivery to individual lambs.

Simulated Flock-Level Shedding Characteristics of Turkeys in Ten Thousand Bird Houses Infected with H7 Low Pathogenicity Avian Influenza Virus Strains.

Understanding the amount of virus shed at the flock level by birds infected with low pathogenicity avian influenza virus (LPAIV) over time can help inform the type and timing of activities performed in response to a confirmed LPAIV-positive premises. To this end, we developed a mathematical model which allows us to estimate viral shedding by 10,000 turkey toms raised in commercial turkey production in the United States, and infected by H7 LPAIV strains. We simulated the amount of virus shed orally and from the cloaca over time, as well as the amount of virus in manure. In addition, we simulated the threshold cycle value (Ct) of pooled oropharyngeal swabs from birds in the infected flock tested by real-time reverse transcription polymerase chain reaction. The simulation model predicted that little to no shedding would occur once the highest threshold of seroconversion was reached. Substantial amounts of virus in manure (median and ; 50% egg infectious dose) were predicted at the peak. Lastly, the model results suggested that higher Ct values, indicating less viral shedding, are more likely to be observed later in the infection process as the flock approaches recovery.

Modelling diagnostics for Echinococcus granulosus surveillance in sheep using Latent Class Analysis: Argentina as a case study

Echinococcus granulosus sensu lato is a globally prevalent zoonotic parasitic cestode leading to cystic echinococcosis (CE) in both humans and sheep with both medical and financial impacts, whose reduction requires the application of a One Health approach to its control. Regarding the animal health component of this approach, lack of accurate and practical diagnostics in livestock impedes the assessment of disease burden and the implementation and evaluation of control strategies. We use of a Bayesian Latent Class Analysis (LCA) model to estimate ovine CE prevalence in sheep samples from the Río Negro province of Argentina accounting for uncertainty in the diagnostics. We use model outputs to evaluate the performance of a novel recombinant B8/2 antigen B subunit (rEgAgB8/2) indirect enzyme-linked immunosorbent assay (ELISA) for detecting E. granulosus in sheep. Necropsy (as a partial gold standard), western blot (WB) and ELISA diagnostic data were collected from 79 sheep within two Río Negro slaughterhouses, and used to estimate individual infection status (assigned as a latent variable within the model). Using the model outputs, the performance of the novel ELISA at both individual and flock levels was evaluated, respectively, using a receiver operating characteristic (ROC) curve, and simulating a range of sample sizes and prevalence levels within hypothetical flocks. The estimated (mean) prevalence of ovine CE was 27.5% (95%Bayesian credible interval (95%BCI): 13.8%–58.9%) within the sample population. At the individual level, the ELISA had a mean sensitivity and specificity of 55% (95%BCI: 46%–68%) and 68% (95%BCI: 63%–92%), respectively, at an optimal optical density (OD) threshold of 0.378. At the flock level, the ELISA had an 80% probability of correctly classifying infection at an optimal cut-off threshold of 0.496. These results suggest that the novel ELISA could play a useful role as a flock-level diagnostic for CE surveillance in the region, supplementing surveillance activities in the human population and thus strengthening a One Health approach. Importantly, selection of ELISA cut-off threshold values must be tailored according to the epidemiological situation.

Risk factors for intramammary infection in meat- and pelt producing ewes with clinically healthy udders

Mastitis is prevalent both in milk- and meat- and pelt producing sheep flocks and is an important disease with substantial effects on economy, animal welfare and antibiotic use, and in dairy flocks also on milk quality and safety. In meat- and pelt producing flocks, the farmers are mainly concerned by clinical mastitis (CM), and most cases of subclinical mastitis (SCM) are not detected and not dealt with, posing a risk for poor udder health in the flock. Studies on risk factors for SCM and/or intramammary infections (IMI) in meat producing flocks are scarce and specific risk factors for weaning and lambing are absent. The aim of this study was therefore to investigate associations between risk factors, at ewe and flock level, for IMI after lambing and at weaning in Swedish meat- and pelt producing ewes with clinically healthy udders. Twenty-two meat- and pelt producing flocks from different parts of Sweden were enrolled in this cross-sectional study. Udder half milk samples were collected at weaning and after lambing from ewes with clinically healthy udders, for bacteriological investigations. Data on ewe and flock level risk factors were recorded. In total, 753 ewes were sampled at least once, and the overall IMI prevalence was 22.5 %. Older ewes, ewes with three or more lambs, ewes that were hard to milk when collecting a milk sample, ewes in moderate size flocks, in flocks with hay as a bedding material and in flocks with less cases of CM had higher risk of IMI. Most of the risk factors associated with IMI in this study differed between weaning and lambing. This study has provided us with novel knowledge on how different factors influence udder health of meat- and pelt producing ewes.

Survey of Salmonella in commercial broiler farms in Shiraz, southern Iran

Salmonella is one of the major causes of food-borne diseases, worldwide. The aim of the present study was to describe the prevalence of Salmonella and to employ a polymerase chain reaction (PCR) assay to confirm the presence of Salmonella Enteritidis and Salmonella Typhimurium in the broiler chicken farms in Shiraz, southern Iran. In addition, risk factors for the presence of Salmonella spp. at farm and flock levels were investigated. Fecal samples were collected from 22 broiler farms, including 35 broiler flocks. Conventional culture methods were used for Salmonella isolation, and the suspected isolates were confirmed by PCR with Salmonella specific primer (invA). Subsequently, PCR was performed to identify S. Enteritidis and S. Typhimurium, using IE-1 and Flic-C primers, respectively. Information for farms and flocks was collected using a questionnaire. Twelve poultry flocks from eight farms were positive for Salmonella. The estimated prevalence of Salmonella was 36.4% at farm level and 34.3% at flock level. Based on the results of PCR, four farms were infected with S. Enteritidis, two farms with S. Typhimurium and one farm with both serovars, concurrently. Statistical analysis using generalized estimating equations showed that at flock level, odds of Salmonella presence increased when the number of chickens was more than 15000 (OR = 13.2, P = 0.023), and an increased odds of Salmonella was found for flocks in which antibiotics were used at sub-therapeutic or therapeutic doses during the rearing period (OR = 19.6, P = 0.003). At the farm level, there was a marginal association between Salmonella and using nipple drinker (OR = 0.08, P = 0.07) and keeping dogs on the farm (OR = 8.9, P = 0.06) by logistic regression analysis. In conclusion, Salmonella spp. including S. Enteritidis and S. Typhimurium are prevalent in the poultry flocks in the region. Considering the results and the fact that the flock size and its surrogate marker, stocking density are among the most consistently identified risk factors for Salmonella in the literature, production cycles with the appropriate number of chicks and proper stocking density are recommended. In addition, careful monitoring and prudent use of antibiotics in poultry farms could be practiced to control this human pathogen in preharvest poultry operations.

Boys (toms) don’t try. Behaviour of turkeys in a Novel Object test – Influence of age and sex

In the present study, a Novel Object test (NOT), designed for turkeys in small groups, was implemented on commercial farms (groups of ~ 5000 animals). The aim of the study was to investigate the reaction of turkeys to novelty in an on-farm setting, which is an approach to assess anxiety-like behaviour and hence might be an appropriate welfare indicator in farm animals. In a pilot study, repeatability of the test design was tested by presenting four different objects simultaneously at different age levels in poultry production. The main study tested the NOT repeatedly on one farm, fattening both female and male birds, with the aim to evaluate sex and age effects in commercial conditions. Data was recorded on three farms, keeping conventionally fattening turkeys (male and female birds), including two fattening periods for pilot studies and four fattening periods for the main study. Novel Object tests were conducted on flock level, using four different novel objects (a bucket, a ball string, a plastic rod and a beach ball). Data were collected by direct observation. The latency up to the first approach, latency up to the first peck, pecking frequency, and the number of animals approaching the object were recorded. Generalised linear mixed models were calculated. Results of the main study found a tendency for the object type to affect the latency to approach the object (F3201 = 2.5; p = 0.06), for all other parameters a significant effect was detected (all F > 2.6; all p < 0.05). Also, sex effects were found to be significant for all parameters measured (all F > 107.2; all p < 0.001), with females showing shorter latency times until the first peck and the first approach, a higher pecking frequency, and more animals approaching the object. The interaction between age and sex was found to be significant for the latency to approach (F6213 = 2.3; p < 0.05). Males showed longer latencies to approach the object in week 5 as compared to all other time points. No differences between time points were found in females. In summary, the results highlight important issues in turkeys’ reaction to novelty, which might be of interest in animal husbandry. Furthermore, results indicate, that further studies are required to validate this behavioural test regarding the interpretation of underlying motivations.

Seroprevalence and Risk Factors of Anaplasma spp. in German Small Ruminant Flocks.

Simple SummaryAnaplasma phagocytophilum and Anaplasma ovis, tick-borne pathogens with zoonotic potential, have been detected in small ruminants in Europe and North America in the past. These intracellular bacteria cause tick borne fever and ovine anaplasmosis, respectively. The most common clinical signs of infection are fever, lethargy and anaemia. To date, little is known about the distribution of these pathogens in sheep and goats from Germany. Therefore, 3178 serum samples of small ruminants from 71 farms distributed in five German federal states (Schleswig-Holstein, Lower Saxony, North Rhine-Westphalia, Baden-Wuerttemberg and Bavaria) were examined for IgG antibodies to Anaplasma species by a cELISA based on the MSP5 antigen. In 70 flocks, antibodies to Anaplasma spp. were detected in both sheep and goats. Furthermore, a risk factor analysis was carried out by means of a questionnaire answered by the farmers. Older animals and females were more likely to have antibodies to Anaplasma spp. Moreover, sheep had a higher probability of becoming seropositive than goats. Using flocks for landscape conservation and the presence of cats and dogs on the farm increased the risk of having more than 20% seropositive animals within the flock significantly. Since antibodies to Anaplasma spp. have been detected in almost all flocks (70/71), it can be assumed that Anaplasma spp. might be underdiagnosed in small ruminants from Germany.Knowledge about the distribution of Anaplasma spp. in small ruminants from Germany is limited. Therefore, serum samples were examined from 71 small ruminant flocks (2731 sheep, 447 goats) located in the five German federal states: Schleswig-Holstein (SH), Lower Saxony (LS), North Rhine-Westphalia (NRW), Baden-Wuerttemberg (BW) and Bavaria (BAV). Antibodies to Anaplasma spp. were determined by a cELISA based on the MSP5 antigen. A risk factor analysis at animal and flock level was also performed. Antibodies to Anaplasma spp. were detected in 70/71 flocks without significant difference in the intra-flock prevalence (IFP) between the federal states. The mean antibody levels from sheep were significantly lower in northern Germany (LS, SH) compared to west (NRW) and south Germany (BW, BAV). Sheep had a 2.5-fold higher risk of being seropositive than goats. Females and older animals (>2 years) were more likely to have antibodies to Anaplasma spp. in one third and one quarter of cases, respectively. Flocks used for landscape conservation had a five times higher risk of acquiring an IFP greater than 20%. Cats and dogs on the farms increased the probability for small ruminant flocks to have an IFP of above 20% 10-fold and 166-fold, respectively. Further studies are necessary to assess the impact of Anaplasma species on the health of small ruminants in Germany.

The Diagnostic Challenges of Ovine Pulmonary Adenocarcinoma

Ovine pulmonary adenocarcinoma (OPA), also known as sheep pulmonary adenomatosis and jaagsiekte, is a contagious pulmonary tumor of sheep, characterized by neoplastic proliferation of type II pneumocyte and club cells. OPA is induced by the oncogenic activity of the envelope glycoprotein (Env) of exogenous jaagsiekte sheep retrovirus (JSRV). This disease is associated with significant economic losses in numerous sheep raising countries. The onset of suggestive clinical signs is often late, making difficult the early diagnosis of the disease and timely implementation of control measures on the affected farms. Further, the lack of diagnostic tests that can be performed routinely by veterinary clinicians to accurately assess infected animals (e.g., serological or others) means that the true prevalence at flock level is not known. Imaging diagnostic methods (e.g., ultrasound, X-ray and computed tomography) can be used to support the clinical diagnosis, even in pre-clinical stages in affected flocks. The diagnosis must be confirmed by PCR of nasal excretions or immunohistochemistry and PCR of tumor lesions. No vaccine for OPA has yet been developed. Thus, in this work, we review the main methods of diagnosis of OPA in order to support the clinician in the identification of the disease, avoid underdiagnosis and allow the implementation of suitable measures to prevent and control its spread.

REPROsheep: A model that integrates individual variability to optimise hormone-free reproduction management strategies for a dairy sheep flock

Managing reproduction of a dairy sheep flock without using hormones for oestrus induction and synchronisation is an alternative method that complies with agroecological principles, animal welfare and public health concerns. However, shifting from conventional reproductive management to a hormone-free philosophy means leaving more room for individual intraflock variability in oestrus occurrence. The success of establishing alternative hormone-free reproduction systems relies on managing the variability of ewes’ individual responses, which are themselves influenced by individual characteristics. Therefore, the so-called REPROsheep model was built to study the effects of individual ewes’ characteristics, such as age, body condition score (BCS) or milk yield, on individual responses, as well as the overall productive and reproductive performances of the flock. This dynamic agent-based model (ABM) represents individual reproduction and lactation processes in a hormone-free management context. Outputs at the flock level were simulated using this model. Two dynamic outputs (weekly number of ewes lambing and weekly milk yield) and two punctual outputs (total number of ewes lambing and total milk yield) were simulated. Sensitivity analysis showed that the studied outputs were affected by ewe age, pre-mating BCS and milk-yield distributions in the flock. Increasing average age or pre-mating BCS by 0.5 from a starting point of 2.5 and average milk-yield by 50 L from a starting point of 195 L appeared to increase, for one breeding season, the number of ewes lambing, the concentration of those lambing events over one period, as well as total milk yield, whereas decreasing the average value of these factors by the same amount appeared to produce the opposite effect. Management strategies favouring an optimum age and pre-mating BCS, as well as good milk yield for the individuals of the flock, may thus be a lever for optimising performance, especially lambing distribution over time. Therefore, the REPROsheep model seems relevant to determine how a management strategy (affecting flock structure in terms of age, body condition or production potential) can impact the performance of a dairy sheep flock in the context of hormone-free reproduction.

Assigning Defined Daily/Course Doses for Antimicrobials in Turkeys to Enable a Cross-Country Quantification and Comparison of Antimicrobial Use.

Antimicrobial resistance (AMR) threatens our public health and is mainly driven by antimicrobial usage (AMU). For this reason the World Health Organization calls for detailed monitoring of AMU over all animal sectors involved. Therefore, we aimed to quantify AMU on turkey farms. First, turkey-specific Defined Daily Dose (DDDturkey) was determined. These were compared to the broiler alternative from the European Surveillance of Veterinary Antimicrobial Consumption (DDDvet), that mention DDDvet as a proxy for other poultry species. DDDturkey ranged from being 81.5% smaller to 48.5% larger compared to its DDDvet alternative for broilers. Second, antimicrobial treatments were registered on 60 turkey farms divided over France, Germany and Spain between 2014 and 2016 (20 flocks per country). Afterwards, AMU was quantified using treatment incidence (TI) per 100 days. TI expresses the percentage of the rearing period that the turkeys were treated with a standard dose of antimicrobials. Minimum, median and maximum TI at flock level and based on DDDturkey = 0.0, 10.0 and 65.7, respectively. Yet, a huge variation in amounts of antimicrobials used at flock level was observed, both within and between countries. Seven farms (12%) did not use any antimicrobials. Aminopenicillins, polymyxins, and fluoroquinolones were responsible for 72.2% of total AMU. The proportion of treating farms peaked on week five of the production cycle (41.7%), and 79.4% of the total AMU was administered in the first half of production. To conclude, not all DDDvet values for broilers can be applied to turkeys. Additionally, the results of AMU show potential for reducing and improving AMU on turkey farms, especially concerning the usage of critically important antimicrobials.

Visna in a UK flock and the biosecurity risk arising from the onward sale of likely infected pedigree stock

AbstractSmall ruminant lentivirus infections in sheep most commonly present with respiratory signs (maedi) and indurative mastitis, while primary neurological signs (visna) have rarely been reported in Great Britain (GB). Most reports of visna describe signs referable to myelitis, although central signs associated with encephalitis may feature. In this case, visna was diagnosed in a 4‐year‐old ewe in a small pedigree sheep flock, recently imported to GB from northern Europe. Initial clinical findings were of a head tilt, circling, facial tremors and a unilaterally reduced menace response. These neurological signs progressed to include hyperaesthesia, ipsilateral hemiparesis and recumbency. Flock level infection had recently been diagnosed by serology, and the diagnosis in this individual case was confirmed by serology and histopathology. The subsequent sale of animals from the flock through a large national auction and at private sales raises significant ethical questions and serves as a reminder of the importance of biosecurity precautions.